A New Idea of Pure Mode-I Fracture Test of Bonded Bi-Materials

2010 ◽  
Author(s):  
Zhenyu Ouyang ◽  
Gefu Ji ◽  
Guoqiang Li ◽  
Su-Seng Pang ◽  
Samuel Ibekwe
Keyword(s):  
Mixed Mode ◽  
Dissimilar Materials ◽  
Test Method ◽  
Interface Fracture ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Fracture Test ◽  
Engineering Structures ◽  
Material Systems

Bi-material systems in which two dissimilar materials are adhesively joined by a thin adhesive interlayer have been widely used in a variety of modern industries and engineering structures. There are two fundamental issues that need to be adequately addressed: (1) Fracture of bonded bi-materials is mixed mode: Mode-I (pure peel) and Mode-II (pure shear). Fracture test implementation of bi-material systems with the traditional Mode-I methods will induce a noticeable mixed mode fracture due to the disrupted symmetry by the bi-material configuration; (2) The popular cohesive zone models (CZMs) for accurate fracture simulations require more than a single parameter (toughness) as is the case in the traditional linear elastic fracture mechanics (LEFM). Thus, J-integral is highly preferred. It can not only capture more accurate toughness value by considering the root rotation effect, but also facilitate the experimental characterizations of the interfacial cohesive laws, which naturally include all required parameters by CZMs. Motivated by these two important issues, a novel idea is proposed in the present work to realize and characterize the pure Mode-I nonlinear interface fracture between bonded dissimilar materials: Despite the approximation with the elementary beam theories, the accuracy is validated by numerical simulations. The proposed approach may be considered as a promising candidate for the future standard Mode-I test method of adhesively bonded dissimilar materials due to its obvious simplicity and accuracy.

On Approximately Realizing and Characterizing Pure Mode-I Interface Fracture Between Bonded Dissimilar Materials

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
Zhenyu Ouyang ◽  
Gefu Ji ◽  
Guoqiang Li
Keyword(s):  
Mixed Mode ◽  
Dissimilar Materials ◽  
Interfacial Fracture ◽  
Interface Fracture ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
J Integral ◽  
Mode I Fracture ◽  
Fracture Behaviors

Bimaterial systems in which two dissimilar materials are adhesively joined by a thin adhesive interlayer have been widely used in a variety of modern industries and engineering structures. It is well known that interfacial fracture is the most common failure mode for these bimaterial systems. Particularly, the interface fracture is a mixed mode in nature mode-I (pure peel) and mode-II (pure shear) due to the disrupted symmetry by the bimaterial configuration. Obviously, characterizing individual fracture modes, especially mode-I fracture, is essential in understanding and modeling the complex mixed mode fracture problems. Meanwhile, the J-integral is a highly preferred means to characterize the interfacial fracture behaviors of a bimaterial system because it cannot only capture more accurate toughness value, but also facilitate an experimental characterization of interfacial traction-separation laws (cohesive laws). Motivated by these important issues, a novel idea is proposed in the present work to realize and characterize the pure mode-I nonlinear interface fracture between bonded dissimilar materials. First, a nearly pure mode-I fracture test can be simply realized for a wide range of bimaterial systems by almost eliminating the mode-II component based on a special and simple configuration obtained in this work. Then, the concise forms of the J-integral are derived and used to characterize the interfacial fracture behaviors associated with classical and shear deformation beam theories. The proposed approach may be considered as a promising candidate for the future standard mode-I test method of bimaterial systems due to its obvious accuracy, simplicity, and applicability, as demonstrated by the numerical and experimental results.

An Evaluation of the Compact Shear Specimen for Mixed Mode Fracture Studies

1983 ◽  
Vol 105 (4) ◽  
pp. 268-272 ◽  
Author(s):  
R. A. Riddle ◽  
R. D. Streit ◽  
I. Finnie
Keyword(s):  
Mixed Mode ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Mode Fracture ◽  
Shear Specimen ◽  
Compact Shear ◽  
Detailed Computer ◽  
Almost All ◽  
Direction Opposite

A compact shear specimen configuration, consisting of three legs with the outer two loaded axially in a direction opposite to the inner one, has been used for several mixed-mode fracture studies. From a detailed computer analysis of this specimen, it is shown that the loading boundary conditions play an extremely important role in determining the state of stress at the crack tip. By simply changing the flexibility of the loading fixture, the specimen can be subjected to a range of mixed mode conditions from almost all Mode I to virtually pure Mode II. Data of other researchers are reviewed in light of this finding. It is shown that by applying loads obliquely to the outer legs pure Mode I loading may also be obtained with this specimen.

New Method for Characterizing Interface Fracture between Dissimilar Materials

2011 ◽  
Vol 374-377 ◽  
pp. 2226-2231
Author(s):  
Jun Long Peng ◽  
Jiao Tang ◽  
Zhen Yu Ouyang
Keyword(s):  
Present Method ◽  
Dissimilar Materials ◽  
Standard Test ◽  
Test Method ◽  
Interface Fracture ◽  
Pure Mode ◽  
Interface Shear ◽  
Hybrid Joints ◽  
Novel Method

The interface fracture process of most layered or bonded structures is commonly under the control of mixed mode cracking where the interface shear and normal fracture components exist simultaneously when the hybrid joints are bonded with different adherend materials. In this work, a simple and novel method is proposed to realize and characterize the pure mode I interface fracture for the hybrid joints with dissimilar substrates. The theoretical and experimental results indicate that the present method may be considered as a standard test method for the characterization of hybrid joints with dissimilar materials.

Evaluation of Generalized MTS Criterion for Mixed-Mode Fracture of Polyurethane Materials

2013 ◽  
Vol 577-578 ◽  
pp. 117-120 ◽  
Author(s):  
Radu Negru ◽  
Liviu Marşavina ◽  
Hannelore Filipescu
Keyword(s):  
Mixed Mode ◽  
Full Range ◽  
Experimental Results ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Bend Specimen ◽  
Mode Fracture ◽  
Fracture Tests

Using the asymmetric semi-circular bend specimen (ASCB) a set of mixed-mode fracture tests were carried out in the full range from pure mode I to pure mode II. The tests were conducted on two polyurethane materials characterized by different properties. The fracture parameters were obtained from experiments and are compared with the predictions based on the generalized MTS criterion (GMTS). The agreement between the experimental results and those predicted based on the GMTS criterion is discussed finally.

scholarly journals Analysis of Mixed-Mode I/II/III Fracture Toughness Based on a Three-Point Bending Sandstone Specimen with an Inclined Crack

2021 ◽  
Vol 11 (4) ◽  
pp. 1652
Author(s):  
Xin Pan ◽  
Jiuzhou Huang ◽  
Zhiqiang Gan ◽  
Shiming Dong ◽  
Wen Hua
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Inclined Crack ◽  
Tangential Strain ◽  
Mode Fracture ◽  
Fracture Parameters ◽  
T Stress

The crack-propagation form may appear as an arbitrary mixed-mode fracture in an engineering structure due to an irregular internal crack. It is of great significance to research the mixed-mode fracture of materials with cracks. The coupling effect of multiple variables (crack height ratio, horizontal deflection angle and vertical deflection angle) on fracture parameters such as the stress intensity factors and the T-stress are the key points in this paper. A three-point bending specimen with an inclined crack was proposed and used to conduct mixed-mode fracture research. The fracture parameters were obtained by finite element analysis, and the computed results showed that the pure mode I fracture and mixed-mode fractures (mode I/II, mode I/III and mode I/II/III) can be realized by changing the deflection angles of the crack. The pure mode I and the mixed-mode fracture toughness of sandstone were obtained by a series of mixed-mode fracture experiments. The experimental results were analyzed with the generalized maximum tangential strain energy density factor criterion considering T-stress. The results showed that the non-singular term T-stress in the fracture parameters cannot be ignored in any mixed-mode fracture research, and the generalized maximum tangential strain energy density factor criterion considering T-stress can better predict the mixed-mode fracture toughness than other criteria.

Fracture Toughness of Structural Ceramics Under Biaxial Stress State by Anticlastic Bending Test

1997 ◽  
Vol 119 (1) ◽  
pp. 7-14
Author(s):  
T. Ono ◽  
M. Kaji
Keyword(s):  
Stress State ◽  
Mixed Mode ◽  
Biaxial Stress ◽  
Bending Test ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Structural Ceramics ◽  
Biaxial Stress State

Mixed-mode fracture of structural ceramics under a biaxial stress state was investigated by an anticlastic bending test using the controlled surface flaw technique. The stress state of the anticlastic bending specimen is biaxial. This test enables the study of fractures under pure mode I, pure mode II, or any combination of mode I and mode II loading. To discuss the experimental results, a parameter “T” was introduced to the modified maximum hoop stress criterion. This parameter represents frictional effects of crack interfaces on the mixed-mode fracture and can be obtained experimentally. Relative magnitudes of mode I and mode II stress intensity factors and the directions of non-coplanar crack extension angles were predicted using the parameter “T.” Reasonable agreement with the experimental results was obtained.

Effect of Crack Length on Mixed-Mode Cohesive Fracture of the Adhesively Bonded Joints

2013 ◽  
Vol 748 ◽  
pp. 231-234
Author(s):  
Reza Bakhtiari ◽  
Ehsan Darabi ◽  
Ali Ravaee
Keyword(s):  
Mixed Mode ◽  
Fracture Behavior ◽  
Test Method ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Bonded Joints ◽  
Loading Conditions ◽  
Adhesively Bonded ◽  
Cohesive Fracture ◽  
Adhesively Bonded Joints

In this paper, the mixed-mode cohesive fracture behavior of adhesively bonded joints was investigated based on numerical analysis. A modified version of Arcan specimen was employed to conduct a mixed-mode fracture test using a special loading device. A full range of mixed-mode loading conditions including pure mode-I and pure mode-II loading were created by ABAQUS software. This test method is a simple procedure, clamping/unclamping the specimens is easy to achieve and only one type of specimen is required to generate all loading conditions. Finite element analyses were carried out on specimens with different adherends in order to investigate deeply about cohesive fracture behavior of adhesively bonded joints.

Characterization of mixed-mode I/II fracture properties of adhesively bonded yellow-poplar by a dual actuator test frame instrument

Holzforschung ◽  
2012 ◽  
Vol 66 (5) ◽  
pp. 623-631 ◽  
Author(s):  
Edoardo Nicoli ◽  
David A. Dillard ◽  
Charles E. Frazier ◽  
Audrey Zink-Sharp
Keyword(s):  
Layer Thickness ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Adhesive Layer ◽  
Mode I ◽  
Pure Mode ◽  
Adhesively Bonded ◽  
Yellow Poplar ◽  
Material Systems ◽  
Test Frame

Abstract Experimental results for the fracture behavior under mixed-mode in-plane loading conditions of adhesively bonded wood specimens are reported. The material systems considered involved yellow-poplar (Liriodendron tulipifera), a hardwood of the Magnoliaceae family, as adherends bonded with two different adhesives, a moisture-cure polyurethane (PU) and a phenol/resorcinol/formaldehyde (PRF) resin. A dual actuator test frame permitted fine scanning of fracture behavior over a full range of mixed-mode I/II levels for double cantilever beam (DCB) geometry specimens. These tests showed that, in the considered material systems, the critical strain energy release rate, c, tends to increase as the mode-mixity of the loading increases. In particular, the increase is steeper in proximity to pure mode II loading for the PRF bonded specimens. The experimental values of c obtained were fairly scattered, as is common when testing wood systems. This variability is due in part to the natural variability of wood but also to other factors such as the orientation of the grain in the bonded beams and variations of bondline thickness. In particular, measurements of adhesive layer thickness were performed. This analysis was implemented with microscopic examination of samples cut from untested DCB specimens, where the bondline had not been disrupted by the test. Although the wood parts were power planed prior to bonding, rather large variations of the adhesive layer thickness were observed: on the order of 1–100 μm for specimens bonded with the PU resin and 10–50 μm for specimens bonded with the PRF resin, which showed somewhat more consistent fracture behavior.

Fracture Toughness of Structural Ceramics Under Biaxial Stress State by Anticlastic Bending Test

1995 ◽  
Author(s):  
Takashi Ono ◽  
Masaki Kaji
Keyword(s):  
Stress State ◽  
Mixed Mode ◽  
Biaxial Stress ◽  
Bending Test ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Structural Ceramics ◽  
Biaxial Stress State

Mixed-mode fracture of structural ceramics under biaxial stress state was investigated by an anticlastic bending test using the controlled surface flaw technique. The stress state of the anticlastic bending specimen is biaxial. This test enables the study of fractures under pure mode I, pure mode II, or any combination of mode I and mode II loading. To discuss the experimental results, a parameter ‘T’ was introduced to the modified maximum hoop stress criterion. This parameter represents frictional effects of crack interfaces on the mixed-mode fracture and can be obtained experimentally. Relative magnitudes of mode I and mode II stress intensity factors and the directions of non-coplanar crack extension angles were predicted using the parameter ‘T’. Reasonable agreement with the experimental results was obtained.

Differences between 2D and 3D Interlaminar Fracture Analysis of Unidirectional Carbon/Epoxy Arcan Specimens: Numerical and Experimental Approaches

2012 ◽  
Vol 626 ◽  
pp. 575-579
Author(s):  
Reza Bakhtiari ◽  
Naghdali Choupani ◽  
Ehsan Darabi
Keyword(s):  
Mixed Mode ◽  
Loading Condition ◽  
Simple Procedure ◽  
Full Range ◽  
Shear Loading ◽  
Test Method ◽  
Mixed Mode Fracture ◽  
Pure Mode ◽  
Loading Conditions ◽  
Interlaminar Fracture

In this paper, the mixed-mode interlaminar fracture behavior of unidirectional carbon-epoxy composite was investigated based on experimental and numerical analysis. A modified version of Arcan specimen was employed to conduct a mixed-mode fracture test using a special loading device. A full range of mixed-mode loading conditions including pure mode-I and pure mode-II loading were created and tested. This test method is a simple procedure, clamping/unclamping the specimens is easy to achieve and only one type of specimen is required to generate all loading conditions. Also, the correction factors were determined via two-and three-dimensional analysis and the results were compared. Results indicated that the interlaminar cracked specimen is tougher in shear loading condition and weaker in tensile loading condition.

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